PHP calls the camera for real-time video encoding: practice from input to output-PHP Tutorial-php.cn

PHP calls the camera for real-time video encoding: practice from input to output

王林

Release： 2023-08-03 08:12:01

Original

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PHP calls the camera for real-time video encoding: practice from input to output

Abstract:
This article will introduce how to use PHP to call the camera for real-time video encoding. We will achieve this by using PHP's FFI extension and calling the ffmpeg library.

Keywords:
PHP, camera, video encoding, FFI, ffmpeg

Introduction
With the advancement of modern technology, more and more applications require Live video processing. As a language widely used in web development, PHP often hopes to use PHP to process video streams. This article will introduce how to use PHP to call the camera for real-time video encoding, realizing the entire process from input to output.
Preparation
First, we need to install the ffmpeg library and the FFI extension of PHP. It can be installed through the following command:
```
sudo apt-get install ffmpeg
sudo pecl install ffi
```
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Writing code
The following is a sample code that demonstrates how to use PHP to call the camera for real-time video encoding.

avformat_alloc_context();
$source = "/dev/video0";
$ffi->avformat_open_input(FFI::addr($formatContext), $source, null, null);
$ffi->avformat_find_stream_info($formatContext, null);

// 查找视频流
$videoStreamIndex = -1;
for ($i = 0; $i < $formatContext->nb_streams; $i++) {
    if ($formatContext->streams[$i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
        $videoStreamIndex = $i;
        break;
    }
}

if ($videoStreamIndex == -1) {
    die("未找到视频流");
}

// 获取视频流信息
$videoCodecPar = $formatContext->streams[$videoStreamIndex]->codecpar;
$videoCodec = $ffi->avcodec_find_decoder($videoCodecPar->codec_id);
$codecContext = $ffi->avcodec_alloc_context3($videoCodec);
$videoFrame = $ffi->av_frame_alloc();
$packet = $ffi->av_packet_alloc();
$frameInfo = FFI::new("AVFrameInfo");

// 设置解码器上下文参数
$ffi->avcodec_parameters_to_context($codecContext, $videoCodecPar);
$ffi->avcodec_open2($codecContext, $videoCodec, null);

while ($ffi->av_read_frame($formatContext, $packet) >= 0) {
    // 解码视频帧
    if ($packet->stream_index == $videoStreamIndex) {
        $ffi->avcodec_send_packet($codecContext, $packet);
        while ($ffi->avcodec_receive_frame($codecContext, $videoFrame) >= 0) {
            // 获取视频帧信息
            $frameInfo->width = $videoFrame->width;
            $frameInfo->height = $videoFrame->height;
            $frameInfo->size = $ffi->av_image_get_buffer_size($videoFrame->format, $videoFrame->width, $videoFrame->height, 1);
            $frameInfo->format = $videoFrame->format;
            
            // 分配输出缓冲区
            $outBuffers = FFI::new("uint8_t[4]");
            $outLinesizes = FFI::new("int[4]");
            
            $ffi->av_image_alloc(FFI::addr($outBuffers), FFI::addr($outLinesizes), $frameInfo->width, $frameInfo->height, $frameInfo->format, 1);
            
            // 复制解码后的图像数据到输出缓冲区
            $ffi->av_image_copy($outBuffers, $outLinesizes, $videoFrame->data, $videoFrame->linesize, $frameInfo->format, $frameInfo->width, $frameInfo->height);
            
            // 输出图像数据，可以自行处理例如将图像数据发送给Web页面的Canvas元素
            // 这里只是简单地输出一帧的数据
            echo $outBuffers[0];
            
            // 释放输出缓冲区
            $ffi->av_freep($outBuffers);
        }
    }
    
    $ffi->av_packet_unref($packet);
}

// 释放资源
$ffi->av_frame_free(FFI::addr($videoFrame));
$ffi->avcodec_close($codecContext);
$ffi->avcodec_free_context($codecContext);
$ffi->avformat_close_input(FFI::addr($formatContext));

?>

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Conclusion
This article introduces how to use PHP to call the camera for real-time video encoding. By using PHP's FFI extension and the ffmpeg library, we can easily output the camera's video stream to other devices or web pages. I hope this article can be helpful to developers who use PHP for video processing.

References:

https://github.com/PHPFFI/PHPFFI
https://www.ffmpeg.org/documentation. html

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